The present disclosure relates generally to bending machines for bending work pieces.
More particularly, the present disclosure relates to bending machines for bending metal work pieces, and particularly for bending metal plates having a relatively large thickness, such as those metal plates having a thickness that is greater than or equal to ⅜ of an inch. Such plates can be made from steel, iron, copper, etc. A great amount of force can be required to bend such metal plates in order to form various metal shapes. In one application, thick steel plates can be bent to a desired shape and used as spring plates for suspension systems on larger and heavier vehicles such as commercial trucks and trailers, construction vehicles, large dump trucks, military vehicles, etc.
Conventional bending methods for such thick metal plates can include placing the metal plate over a bending anvil, and applying a bending force on the metal plate to conform the metal plate to the shape of the bending anvil. Because of the large amount of force needed to bend thicker metal plates, the bending force is generally applied in a cantilevered fashion, with the force applied at a substantial distance from the anvil where bending occurs, in order to increase the leverage and moment applied to the metal plate by the bending force. Doing so can help reduce the force and energy needed to bend the metal plate. However, separating the bending force from the point of bending can allow the metal plate to bend, bow, twist, or deflect along a length of the plate between the bending anvil and the application point for the bending force. Such bending can cause the edges of the metal plate to flare or bevel, and particularly at the bend site, which is undesirable.
Additionally, conventional machines for bending thick metal plates such as wipe dies and press brake dies utilize forming or bending punches that apply the bending force to the metal plate. However, such bending punches are configured such that they produce friction forces on a surface of the metal plate as the bending force is applied to the metal plate. Because of the large bending force required to bend the thick metal plates, the friction forces produced during bending can negatively affect the surface integrity of the plates and can cause deformation points on the metal plate which can produce a localized failure point in the final product that can adversely affect the lifespan of the final product. Such failure points can also produce a safety hazard if the products fail unexpectedly during use.
Additionally, such applied friction forces can deform or damage the edges of predrilled holes or recesses formed in the metal plate prior to bending. As such, the desired holes or recess often must be reformed after the bending process is complete, which can be cumbersome and is generally undesirable.
What is needed then are improvements to bending machines, and particularly for bending machines for thick metal plates.